1. Technical Field
The present invention is concerned with comparing one pattern with another, and is of particular interest in the comparison of two-dimensional patterns such as visual images, although applicable also to one-dimensional patterns and patterns having three or more dimensions.
2. Related Art
Standard approaches to pattern recognition use templates to recognize and categorize patterns [1]. Such templates take many forms, but they are normally produced by a statistical analysis of training data and matched with unseen data using a similarity measure [2]. The statistical analysis is normally carried out over a number of intuitively selected features that appear to satisfy the needs of the recognition task. For example, in speech recognition, templates can be encapsulated as Hidden Markov Models derived in the frequency domain and, in Optical Character Recognition, the templates take the form of the character fonts themselves. In the case of face recognition, a number of intuitively chosen features such as skin texture, skin color and facial feature registration are used to define face templates. In a CCTV surveillance application, intruders are normally detected through a process of frame subtraction and background template modelling which detects movement and removes background effects from the processing [3]. In many cases, the number of features leads to a computationally unmanageable process and Principal Components Analysis and other techniques are used to scale down the problem without significantly reducing performance (e.g., see partek.com website/index.html). These approaches achieve great success in non-noisy environments, but fail when the pattern variability and number of pattern classes increase.
Some techniques for analysis of images or other patterns where the pattern is compared with other parts of the same pattern are described in our earlier patent applications as follows.
European patent application 00301262.2 (publication No. 1126411);
International patent application PCT/GB01/00504 (publication No. WO 01/61648);
International patent application PCT/GB01/03802 (publication No. WO 02/21446);
U.S. patent application Ser. No. 977,263/09 filed 16 Oct. 2001 (publication No. 20020081033);                as well as the following papers published by the inventor:            Stentiford F W M, “An estimator for visual attention through competitive novelty with application to image compression”, Proc. Picture Coding Symposium 2001, Seoul, 25-27 April, pp 101-104, 2001.    Stentiford F W M, “An evolutionary programming approach to the simulation of visual attention”, Proc. Congress on Evolutionary Computation 2001, Seoul, pp 851-858, 27-30 May, 2001.